Petrovic made her first WWE appearance in November 2022 on NXT, under the name Monika Klisara. In 2023, she made her debut on the July 28 episode of NXT Level Up, appearing as Karmen Petrovic in a match won by Ivy Nile. On the October 17 episode of NXT, Petrovic gained her first televised singles victory when she competed in the 2023 NXT Women's Breakout Tournament, during which she eliminated Jaida Parker in the first round. The following week, on the October 24 episode of NXT, Petrovic was eliminated in the semifinal round by Lola Vice.
On the July 2, 2024 episode of NXT, Petrovic went one on one with Jazmyn Nyx, but lost due to interference from Jacy Jayne. This would set up a tag team match between Petrovic and Arianna Grace against Jazmyn Nyx and Jacy Jayne at NXT Heatwave on July 7, which Petrovic and Grace won. After the match, Grace and Petrovic had a disagreement on who contributed to the match victory, to which NXT General Manager Ava scheduled a match between them. In late September, Petrovic started a romance storyline with Ashante "Thee" Adonis. On the November 19 episode of NXT, Petrovic and Adonis teamed up for the first time to defeat Brinley Reece and Dion Lennox in a mixed tag team match.